Owyhee Valley
Idaho
Find: Opal, rhyolite, chalcedony, possible thundereggs.
GPS: 43.4656, -116.86577 (start of road)
Nearest city: Boise, ID
Recommended Vehicle: AWD + high-clearance
Summary:
This is one of the most popular rockhounding spots on my channel. I was given specific GPS coordinates by a friendly stranger in Oregon.
I always keep rock hunting spots given to me by individuals private. The coordinates listed take you to the start of Sommer Camp Road. There are numerous opal deposits if you follow the road Southeast and turn down one of the many dirt roads. Be mindful of mining claims, there are some active ones in this region.
You will want AWD and decent ground clearance. Wet weather will make access very difficult. Off-road tires would be very beneficial.
Video Guide
Check out the video for a better look at what can be found when exploring this spot.

I've still got this one waiting for the day I have access to a big saw.

My favorite find from the Owyhee Valley. I am unsure if this is considered "Spencer Opal".

Prepare for possible snow if you visit Idaho in late Fall.

Many of the opal in host rock busted free with use of a small geology pick.

A chisel and hammer may come in handy, however.

I found the best specimens towards the peaks of the hills, where large opals seemed to have been mined from the rhyolite.

You can also find chalcedony formations like this. Thundereggs may be present, but this is something I heard rather than saw.

Got my money's worth on the Firestone all season tires.